1. Field of the Invention
The present invention relates to high efficiency solid state thermal neutron detectors, and more specifically, it relates to process design for high thermal neutron efficiency and high gamma rejection.
2. Description of Related Art
Solid-state thermal neutron detectors are required for a variety of applications, particularly, nonproliferation of special nuclear material (SNM). The currently used technology involves 3He tubes, which have a variety of shortcomings when utilized in the field as thermal neutron detectors, including the need for high-voltage operation, sensitivity to microphonics, and large size. Moreover, given that the world's supply of 3He is limited, this presents yet another set of critical issues related to strategic and tactical implications, which are of practical importance.
A variety of solid-state thermal neutron detectors have been proposed, which often involve trade-offs between thermal neutron detection efficiency and gamma discrimination, which are two key performance metrics. As an example, by modifying the detector geometry and composition, one can, in general, increase the neutron detection efficiency. However, improving this metric can result in greater false positives and false negatives. That is, in the present art, increasing the sensitivity of the device to detect thermal neutron events can result in a concomitant increase in the response of the detector to gamma ray events. Since the electrical output signature of the detector for neutron and gamma events is typically similar, neutron events can be misinterpreted as gamma events, and, vice versa. It is desirable to provide sensor designs, as well as different fabrication processes, to realize a robust detector that simultaneously achieves high thermal neutron detection efficiency, with high levels of gamma discrimination.